The invention relates to a method and apparatus for handling and more particularly packaging flat articles such as stationery envelopes.
Stationery envelopes of paper, that is to say both letter envelopes and also mailing bags, are as a rule produced of single-piece, multi-folded cutouts. It is a known practice to connect together neighboring edges of the folded cutouts with the aid of folded over adhesive flaps. At the openings for filling, the closing flaps which lie flat, are kept in the unbonded condition. After manufacture in a production machine the stationery envelopes are packed in stacks of for instance 500 or 1000 pieces in cartons. In the area of the closing flaps of each stationery envelope in a stack only two paper plies rest on top of each other, whereas in the area of the adhesively bonded side edges three paper plies are resting on top of each other. Thus, one and the same stationery envelope has in the empty state at different locations differences in thickness which amount to a third of the maximum thickness. A stack with many stationery envelopes is for this reason substantially thicker in the area of the bonded flaps than adjacent to edges which are merely folded. In order to compensate for this different thickness of the letter envelopes it is a known practice to manually pack the envelopes in small stacks, which are offset by 180xc2x0, directly in shipping cartons.
Furthermore, the European Patent Publication EP 0 506 606 B1 discloses a method and a device for packaging stationery envelopes in boxes, wherein the stationery envelopes coming from a production machine as an upright endless stack are first divided up into partial stacks and then pushed off the conveyor belt into an auxiliary device while maintaining their position. The auxiliary device holds the partial stack pushed off the conveyor belt until it is accepted by a movable entraining carrier, which deposits the stack in a movably arranged collecting basket, which is at least alternatingly able to be turned about a basket axis which is perpendicular to the stack. In this collecting basket the partial stacks in different positions are then first collected and then jointly removed from it, then pressed together and pushed into a box held ready.
This method and the respective device are expensive and complicated. The device comprises a plurality of different components, which are not only expensive to produce but are also problematical in operation and liable to failure. A particular problem is the ever recurring need for resetting to different stationery envelope formats.
The invention aims at providing a simple, reliable, low-cost method for a positionally accurate turning over of flat articles and more particularly stationery envelopes. The method shall be easily adaptable to different formats. The invention also aims at providing a suitable device for these purposes with a compact construction for the handling of articles or stationery envelopes coming from a production machine. They can then be further processed or preferably put in stacks and packaged. At least in the case of stationery envelopes the articles will have the same or a different thickness of their material at the same positions.
In order to achieve this object the invention provides, that first a plurality of flat articles or stationery envelopes are lifted up as partial stacks and then deposited at another location and that the partial stacks on raising and/or lowering (rearranging) are so moved that the articles or stationery envelopes after depositing stand on the same side or edge as originally or on another side or edge.
In accordance with the invention the stationery envelopes are no longer first collected in groups of partial stacks in a collecting basket serving as an intermediate storage, with, respectively, different alignments and then directly transferred to a shipping carton. Rather, the articles are placed immediately after the production machine in groups of partial stacks selectively on any desired edge or, respectively, selectively on one of their margins. Stacks of any desired size may be then formed from the partial stacks, for example for packing and after reaching the intended size may for example be transferred to a packing station.
Instead of stationery envelopes it is however also possible for hygienic articles and other flat articles, in the case of which there may be similar problems, to be processed using the intermediate steps in accordance with the invention and then further processed and/or packed in any desired fashion. This possibility-covers cases in which the articles or, respectively, stationery envelopes are not made ready for a boxing device but also for a bundling device, where they may be provided with a band and held together, whereupon they are either packaged as a small partial stack in cellophane or boxed as a larger stack.
For lifting and lowering the partial stacks a turning station is employed in accordance with the invention, which comprises at least one movable carrier, which may be a movable arm. At the free end of this arm or carrier at least one also movable gripper is arranged, which is capable of gripping a partial stack and after the rearrangement releasing it again.
As a further development of the invention it is possible for the gripper to be movable about a gripper axis parallel to a pivot or rotation axis of the carrier and/or about a gripper axis perpendicular thereto, whereby it is possible to satisfy any conceivable requirements.